Liquid crystal display and battery label including a liquid crystal display

ABSTRACT

A liquid crystal display of the present invention includes a first electrode provided on a substrate, a first liquid crystal layer provided on and in contact with the first electrode, a second electrode provided on and in contact with the first liquid crystal layer, a second liquid crystal layer provided on and in contact with the second electrode, and a third electrode provided on and in contact with the second liquid crystal layer. The display may further include a third liquid crystal layer provided on and in contact with the third electrode, and a fourth electrode provided on and in contact with a third liquid crystal layer. By reducing the thickness of the liquid crystal layers relative to a conventional liquid crystal display, and by providing a plurality of liquid crystal layers, the voltage level required to cause the liquid crystal display to change visual states is substantially reduced without affecting the degree of visual change exhibited by the liquid crystal display. Preferably, at least one of the electrodes is formed of a transparent processable conductive polymer, which is much less expensive than the conventional tin-doped indium oxide materials typically used to form a transparent electrode. The liquid crystal display of the present invention is preferably incorporated in a battery label to display information pertaining to the battery, such as the discharge level of the battery.

BACKGROUND OF THE INVENTION

The present invention generally relates to liquid crystal displays andbattery tester circuits, and more particularly to battery testercircuits of the type that may be printed on a battery label.

Battery tester circuits exist that may be printed on a battery label.Such existing battery tester circuits are typically either"thermochromic" testers or "electrochromic" testers. Thermochromictesters include a calibrated resistor that is selectively coupled to theopposite poles of the battery through a switch that may be provided ateither or both ends of the calibrated resistor. A thermochromic ink isprinted over the resistor that responds to changes in temperature of thecalibrated resistor to gradually change between opaque and transparentstates and thereby enable indicia printed under the thermochromic layerto be viewed or blocked based upon the temperature of the calibratedresistor. Alternatively, the thermochromic layer may change colors inresponse to the temperature of the calibrated resistor. The temperatureof the calibrated resistor is determined by the power which the batterycan deliver, which is a function of both the voltage and internalresistance of the battery. The accuracy of a thermochromic tester isdetermined by not only the rate of change of the open circuit voltageand internal resistance (rate of change of the battery's ability toproduce power), but also the sharpness of the color change in thethermochromic ink (the number of degrees of temperature change requiredto make the thermochromic ink change color). Thus, the thermochromic inklayer functions both as a display and temperature sensor.

Electrochromic testers differ from thermochromic testers in that thedisplay layer changes color directly in response to the open circuitvoltage of the battery. The accuracy of an electrochromic tester isdetermined by the rate of change of the open circuit voltage of thebattery with depth of discharge and the sharpness of the change ofintensity of the electrochromic display with voltage. Thus, like thethermochromic tester, the electrochromic tester display functions bothas a display and a voltage sensor and the accuracy of the tester may belimited by the voltage response of the display.

Since the accuracy of these thermochromic and electrochromic testers islimited by the response of the display, it has been proposed to improvetester accuracy by including a voltage-responsive electronic component,such as a Zener diode or transistor and to thus limit the function ofthe display to that of a display. Such an approach is disclosed in U.S.Pat. Nos. 5,610,511, 5,460,902, and 5,389,470. In these patents, atester circuit is disclosed that utilizes discrete electronic componentsto discriminate between various discharge levels and to selectivelyactivate different segments of a thermochromic display. Thus, thesetester circuits provide discrete displays for the various dischargelevels that may be discriminated by the separate sensing circuit therebylimiting the function of the display to that of a display. However,because the testers disclosed in these patents utilize discreteelectronic components manufactured using conventional semiconductortechnology, the electronic components are not small enough to beincluded in the label of a battery. Further, because the exteriordimensions of batteries are strictly limited by the ANSI standards, suchelectronic components cannot be provided on the exterior surface of thebattery. If such electronic components were to be provided in theinterior of the battery, the space occupied by the electronic componentswould reduce the space in which the active battery ingredients areprovided thereby reducing the service life of the battery. For thesereasons, the use of a separate voltage discrimination circuit for anon-label tester has not been commercially implemented.

Another problem associated with thermochromic and electrochromic testersconcerns the amount of power consumed by these testers. Because thesetesters consume relatively significant levels of power, switches areprovided to enable selective activation of the testers without requiringa constant drain on the battery. Because of the requirement for suchswitches, however, the displays do not continuously display the currentdischarge level of the battery.

Although general purpose electric field-responsive liquid crystaldisplays are known, they are too expensive to include on a battery labeland they require activation voltage levels well in excess of the opencircuit voltage of most batteries. Further, these liquid crystaldisplays tend to irreversibly polarize when driven using a directcurrent (DC) driving signal. For these reasons, field-responsive liquidcrystal displays have been considered to be unsuitable for use in anon-label battery tester.

SUMMARY OF THE INVENTION

Accordingly, it is an aspect of the present invention to solve the aboveproblems and to provide a liquid crystal display that requiressignificantly lower voltages for driving the display. It is anotheraspect of the present invention to provide a liquid crystal display thatmay be incorporated in a battery label at a relatively low cost.

To achieve these and other aspects and advantages, the liquid crystaldisplay of the present invention comprises a first electrode provided ona substrate, a first liquid crystal layer provided on and in contactwith the first electrode, a second electrode provided on and in contactwith the first liquid crystal layer, a second liquid crystal layerprovided on and in contact with the second electrode, and a thirdelectrode provided on and in contact with the second liquid crystallayer. The liquid crystal display may further include a third liquidcrystal layer provided on and in contact with the third electrode, and afourth electrode provided on and in contact with the third liquidcrystal layer. By providing a plurality of such liquid crystal layers,the voltage required to cause the liquid crystal layers to change visualstates is substantially reduced without reducing the overall degreethrough which the liquid crystal display changes visual states.

Preferably, at least one of the electrodes is made of a transparentprocessable conductive polymer. Because processable conductive polymersare less expensive than the commonly used tin-doped indium oxide (ITO)materials, the overall cost of the display may be significantly reducedby using processable conductive polymers for the electrodes.

These and other features, advantages, and objects of the presentinvention will be further understood and appreciated by those skilled inthe art by reference to the following specification, claims, andappended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a perspective view of the battery incorporating an on-labelbattery tester constructed in accordance with a first embodiment of thepresent invention;

FIG. 2A is a partial cross-sectional view taken along plane 2A--2A ofFIG. 1 illustrating a liquid crystal display configuration constructedin accordance with a first variation of the first embodiment of thepresent invention;

FIG. 2B is a partial cross-sectional view taken along plane 2A--2A ofFIG. 1 illustrating a second variation of a liquid crystal displayconstructed in accordance with the present invention;

FIG. 3 is an electrical circuit diagram in block form of a batterytester circuit constructed in accordance with a first embodiment of thepresent invention;

FIG. 4 is a perspective view of a battery constructed in accordance witha first embodiment of the present invention and having a protectiveouter layer removed to show the positioning of the elements on a baselayer of a battery label;

FIG. 5 is an electrical circuit diagram in block and schematic formshowing an exemplary construction of a voltage discriminating circuitconstructed in accordance with the present invention;

FIG. 6 is a cross-sectional view of an exemplary transistor that may beprinted on a label using conductive and semiconductive inks;

FIG. 7 is an electrical circuit diagram in schematic form illustratingan exemplary oscillating circuit for use in the battery tester circuitof the present invention;

FIG. 8 is an electrical circuit diagram in block form illustrating abattery tester circuit constructed in accordance with a secondembodiment of the present invention; and

FIG. 9 is an electrical circuit diagram in block form illustrating abattery tester constructed in accordance with a third embodiment of thepresent invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1 shows a battery 10 having a label 15 incorporating a batterytesting circuit constructed in accordance with the present invention. Asexplained in more detail below, the battery testing circuit includes adisplay 20 for indicating the relative discharge level of battery 10.Preferably, display 20 is a multi-segmented display having a pluralityof segments 22a-22c that may be selectively activated so as to moreaccurately display the discharge level of battery 10. For example, afirst segment 22a may be exposed to indicate "fresh" when the remainingbattery capacity is relatively high, a second segment 22b that shows anindication of "good" when the battery discharge level is sufficient formost applications, and a third segment 22c for showing a "replace"indication when the remaining battery capacity is too low for use inmost applications.

Although the display is described herein as being provided primarily foruse in connection with a battery tester, it will be appreciated that thedisplay may be provided on a battery label to display other informationpertaining to the battery. Such information may include advertisementsand/or other information or graphics for attracting a consumer'sattention. Given that the disclosed display may be continuously left inan ON state, the displayed information may periodically alternatebetween a graphic advertisement and the battery discharge level, forexample. Further, a switch may be provided in the battery label tomanually initiate a change in the information displayed.

In a preferred embodiment of the present invention, display 20 is aliquid crystal display having one of the two structures shown in FIGS.2A and 2B. Most preferably, display 20 is an electric field-responsiveliquid crystal display. An electric field-responsive liquid crystaldisplay includes at least one layer of liquid crystal material thatundergoes a change in visual appearance in response to an electric fieldapplied across the layer of liquid crystal material. Suchfield-responsive liquid crystal displays may, for example, bebirefringent or bipolar.

As shown in FIG. 2A, a liquid crystal display 20 may include a graphicslayer 30 that may be printed on a label substrate 32 using conventionalprinting techniques. Label substrate 32 may be a laminated orsingle-layer structure and is preferably formed of at least one layer ofPVC material. Graphics layer 30 may be formed of conventional inks toprovide high contrast indications such as "fresh," "good," and"replace." The indications printed in graphics layer 30 may beselectively blocked or made viewable by the selected activation of acorresponding segment (22a-22c) of a liquid crystal material layer 36provided between a first electrode 34 and a second electrode 38.Separate sets of electrodes 34 and 38 are preferably provided for eachdisplay segment 22a-22c. Such segments may be completely isolated fromone another or share a common liquid crystal layer. Preferably, firstand second electrodes 34 and 38 are formed of a transparent conductivematerial such as ITO or, more preferably, a much less-expensive solutionprocessable conductive polymer such as dodecylbenzene sulfonic aciddoped polyaniline which is dissolved in toluene solution for printingthe transparent electrodes on the adjacent layers. Electrodes 34 and 38may also be formed of thin transparent metal coating formed by vapordeposition or sputtering, or of printing inks that use transparentconductive particles such as tin-doped indium oxide, antimony-doped tinoxide, fluorine doped tin oxide, or zinc oxide.

It will be appreciated by those skilled in the art that the bottomelectrode 34 may be reflective rather than transparent. If electrode 34is reflective, or opaque, graphics layer 30 is preferably formed on topof electrode 34 so that it will be visible through liquid crystal layer36.

Liquid crystal layer 36 is preferably formed of a polymer liquid crystal(PLC) or polymer-dispersed liquid crystal (PDLC) material that may beprinted on an adjacent layer using conventional printing techniques. Fora PLC display, polymers with conventional liquid crystal materials areused in place of the liquid crystal materials. Such PLC displays aredisclosed in U.S. Pat. No. 5,397,503, the disclosure of which isincorporated herein by reference.

For a PDLC display, the liquid crystal material is isolated either inmicrocapsules imbedded in a solid polymer matrix or in micelles in apolymer matrix. The polymer matrix is preferably chosen so that thepolymer and liquid crystal material have equal refractive indices in thepresence of an electric field. When the indices are the same, thematerial appears clear. When the electric field is removed, therefractive indices become different and the incident light is scatteredand the material appears cloudy or black with suitable dye additives.Examples of such birefringent PDLC displays are disclosed in U.S. Pat.Nos. 5,202,063, 5,285,299, and 5,225,104.

Display 20 also preferably includes one or more protective layers 40made of a transparent material such as PVC or the like. It will beappreciated by those skilled in the art that layers 30, 34, 36, and 38may be printed first on label substrate 32 and then adhered toprotective layer 40 or alternatively may be printed on protective layer40 in reverse order and then adhered to label substrate 32. Alternativemethods of forming this and the other structures disclosed herein willbe apparent to those skilled in the art.

FIG. 2B shows an alternative construction for a printed liquid crystaldisplay 20. In this alternative construction, a plurality of thinnerliquid crystal layers are used in place of the thicker liquid crystallayer 36 described above in FIG. 2A. By using a plurality of thinnerliquid crystal layers, the voltage required to activate and drive theliquid crystal display 20 may be significantly reduced. A plurality ofsuch thinner liquid crystal layers are preferred because the thinner theliquid crystal layer, the less perceptible its change in visual states.In this manner, the change in visual states of each liquid crystal layerwill be cumulative thereby providing a sufficient overall change invisual appearance of the display between its activated and inactivatedstates. For the single layer display shown in FIG. 2A, liquid crystallayer 36 has a thickness of 1.5 to 2.0 microns and is preferably poweredby applying a 4- to 5-volt field across layer 36. In the display shownin FIG. 2B, the liquid crystal layers are thin enough such that a fieldof 1.5 volts need only be applied across each layer to cause a change invisual states.

As shown in FIG. 2B, a graphics layer 30 is preferably printed on alabel substrate 32 in the same manner as described above with respect toFIG. 2A. A first transparent electrode 42 is subsequently printed ongraphics layer 30. On transparent electrode 42 is printed a first liquidcrystal layer 44. A second transparent electrode 46 is printed on anopposite side of liquid crystal layer 44. A second liquid crystal layer48 is printed on second transparent electrode 46, and a thirdtransparent electrode 50 is printed on second liquid crystal layer 48.Tester display 20 may further include a third liquid crystal layer 52printed on third transparent electrode 50 and a fourth transparentelectrode 54 printed on third liquid crystal layer 52. A protectivelayer 56 may also be provided over the structure in the same manner asdescribed above with respect to FIG. 2A. Because each liquid crystallayer in the structure shown will be activated at the same time,alternating transparent electrodes are preferably electrically coupledtogether such that only two electrical connectors 58 and 60 need to beprovided for delivering power to activate the display.

As with the embodiment illustrated in FIG. 2A, the embodiment of thedisplay 20 illustrated in FIG. 2B includes liquid crystal layers thatare preferably formed of PLC or PDLC materials. Further, the transparentelectrodes are preferably formed of a solution and processableconductive polymer. Such materials are relatively inexpensive and areparticularly well-suited for printing the layers on a substrate oradjacent layer as is desirable for mass production of such testerdisplays.

As mentioned above, the battery testing circuit preferably utilizes adisplay 20 that is used solely for the purpose of displaying informationto the consumer. To this end, a separate voltage discriminating circuit70 compares the sensed open circuit voltage of the battery to generatedreference values to determine whether the remaining cell capacity of thebattery is fresh, good, or fully discharged. It will be appreciated bythose skilled in the art that if additional display segments areprovided, voltage discriminating circuit 70 would preferably classifythe sensed open circuit voltage in additional classifications tocorrespond to the number of display segments.

Because the voltage required to drive liquid crystal display 20 mayexceed that of the open circuit voltage of the battery, and because theelectric field responsive-type liquid crystal displays described aboveare preferably driven using an alternating current (AC) signal ratherthan a direct current (DC) signal, a voltage multiplying/oscillatingcircuit 72 is also included in the battery testing circuit of thepresent invention. As illustrated in FIG. 3, voltagemultiplying/oscillating circuit 72 is coupled to the positive andnegative battery terminals by conductive strips 78 and 80, respectively.Voltage multiplying/oscillating circuit 72 preferably delivers an ACdriving signal over connectors 74 and 76 to voltage discriminatingcircuit 70. The frequency of the AC driving signal generated by circuit72 is preferably less than 10 kHz. The voltage levels of circuit 72 arepreferably in the range of 3 to 50 volts. Although FIG. 3 shows aprovision of the voltage multiplying/oscillating circuit 72 between thebattery terminals and the voltage discriminating circuit 70, thepositioning of these circuits may be reversed such that the voltagediscriminating circuit 70 selectively enables voltagemultiplying/oscillating circuit 72 to deliver an AC driving signal to aselected segment (22a, 22b, or 22c) of display 20. However, by providinga voltage multiplying circuit 72 in the manner shown in FIG. 3, voltagediscriminating circuit 70 will be presented with a greater range ofvoltages thereby increasing its ability to discriminate between variousvoltage levels. Exemplary circuits for implementing voltagediscriminating circuit 70 and voltage multiplying/oscillating circuit 72are described below with reference to FIGS. 5 and 7. As explained below,circuits 70 and 72 are preferably formed by printing processableconductive polymer material layers on a battery label substrate. In thismanner, a battery tester having such circuit components may be printedon a battery label.

FIG. 4 shows a battery 10 with protective layers (40 or 56) removed toexpose the relative positioning of the components of the battery testercircuit as illustrated in FIG. 3. As shown in FIG. 4, conductive strip80 extends along label substrate 32 to an edge thereof in contact withthe negative terminal of battery 10. The negative terminal is typicallyelectrically insulated from the battery can and positive terminal.Because the can is typically electrically connected to the positiveterminal, conductive strip 78 need not extend all the way to thepositive terminal at the end of battery 10, but may contact the batterycan through a hole provided in label substrate 32. A switch pad 82 mayoptionally be provided over the hole in label substrate 32 such that thetester circuit may be selectively coupled to the positive terminal ofthe battery through activation of switch 82 by the consumer. Such aswitch mechanism may be constructed in a conventional manner. With thepreferred construction of the tester circuit of the present invention,however, conductive strip 78 may be permanently electrically connectedto the can of battery 10 or to the positive terminal due to the very lowpower consumption rate of the preferred battery tester circuit. Thus,with such a direct and permanent electrical connection, the batterytesting circuit may continuously monitor the cell capacity and provide acontinuous display of the remaining capacity.

An exemplary circuit for implementing a voltage discriminating circuit70 is shown in FIG. 5. As shown in FIG. 5, voltage discriminatingcircuit 70 may include a resistor dividing network including a firstresistor 90 having a first end connected to connector 74 and a first endof a second resistor 92. As explained with respect to FIG. 3 above,connector 74 is coupled to the positive output terminal of voltagemultiplying/oscillating circuit 72. The second end of first resistor 90is coupled to connector 58 which is coupled to one or more of thetransparent electrodes that are part of liquid crystal display 20.Second resistor 92 has its second end connected to a first end of athird resistor 94 and to a first end of a fourth resistor 96. Thirdresistor 94 has its second end coupled to the gate of a first transistor98. Fourth transistor 96 has its second end connected to a first end ofa fifth resistor 100 and to the first end of a sixth resistor 102. Fifthresistor 100 preferably has its second end connected to the gate of asecond transistor 104. Sixth resistor 102 preferably has its second endconnected to a first end of a seventh resistor 106 and to a first end ofa thermistor 108. Seventh resistor 106 preferably has its second endconnected to the gate of a third transistor 110. The second end ofthermistor 108 is preferably coupled to connector 76 and to the cathodeof a Zener diode 112. The anode of Zener diode 112 is coupled to thedrains of first, second, and third transistors 98, 104, and 110. Thesources of transistors 98, 104, and 110 are respectively coupled toconnector 60a, 60b, and 60c which drive the opposing transparentelectrode in segments 22a, 22b, and 22c, respectively, of liquid crystaldisplay 20.

The details and operation of the voltage discriminating circuit (70)illustrated in FIG. 5, are described in U.S. Pat. No. 4,027,231, thedisclosure of which is incorporated herein by reference. Examples ofother voltage discriminating circuits are disclosed in U.S. Pat. Nos.5,460,902 and 5,610,511.

Voltage discriminating circuit 70 is preferably formed by printing thevarious elements and connectors directly on label substrate 32 or onprotective layer 40 or 56. Techniques for printing resistors in thismanner are known and used in printing thermochromic battery testers.Techniques for printing transistors and diodes using polymers are alsogenerally known and described in an article by Francis Garnier et al.,entitled "All-Polymer Field-Effect Transistor Realized by PrintingTechniques" appearing in Science, Vol. 265, Sep. 16, 1994; and in anarticle by A. R. Brown et al. entitled "Logic Gates Made From PolymerTransistors and Their Uses in Ring Oscillators," Science, Vol. 270, Nov.10, 1995. An example of a transistor printed using such polymers isshown in cross section in FIG. 6.

As shown in FIG. 6, a metal-insulator-semiconductor FET (MISFET)includes an insulating layer 120, which may be formed of a 1.5 μm thickpolyester film polyethylene terephthalate. A gate electrode 122 may beprinted on one of the faces of insulating film 120, a 10 μm thick layerof a conducting graphite-based polymer ink. The MISFET also includes adevice substrate 124, which may be made of a 10×15 mm sized adhesivetape with electrical contact for the gate electrode made from the sameconducting polymer ink. The source 126 and drain 128 layers of theMISFET may be formed using two 1×10 mm strips that are 10 μm layer thickof the same conducting graphite-based polymer ink. Preferably, thesource and drain electrodes 126 and 128 are deposited through a maskwith a 200 μm interelectrode distance. The MISFET further includes anorganic semiconducting layer 130 deposited between the source and drainlayers. Semiconducting layer 130 may be formed of α,ω-di(hexyl)sexithiophene.

FIG. 7 shows an exemplary oscillating circuit 72, which may also beformed using polymer transistors suitable for printing on a substrate.The inverter ring oscillator shown in FIG. 7 is described by A. R. Brownet al. in an article entitled "Logic Gates Made From Polymer Transistorsand Their Uses in Ring Oscillators," Science, Vol. 270, Nov. 10, 1995.As shown, this ring oscillator includes five inverter gates formed of aplurality of MISFETs 132. As described in the above article, theoscillator circuit shown in FIG. 7 has an oscillating frequency in therange of 10-500 Hz. MISFETs 132 may be printed and configured in thesame manner as shown in FIG. 6. Examples of capacitive voltage doublercircuits capable of producing an AC signal at double the input voltageare described in Maxim 1989 Integrated Circuits Data Book, pp. 6-119;and in F. Mazda, Electronic Engineer's Reference Book, 5th Ed.,Butterworths, 1983, Chapters 39 and 42, the disclosures of which areincorporated herein by reference.

FIG. 8 shows a second embodiment of the battery tester circuit of thepresent invention. As shown, the tester circuit according to the secondembodiment includes a display driver circuit 150 for generating anoscillating driving signal that is delivered to respective pairs ofconductive strips 158, 160, 162, 164, 166, and 168 to respectiveelectrodes 170, 172, 174, 176, 178, and 180 of a multi-segmented liquidcrystal display 152. Display driver circuit 150 is connected to thepositive battery terminal by a conductive strip 154 and to the negativebattery terminal by a conductive strip 156. As apparent from acomparison of the tester circuit shown in FIG. 8 to that shown in FIG.3, the voltage discriminating circuit 70 has been eliminated. In thisregard, the voltage discrimination function is carried out by the liquidcrystal display 152. Because the liquid crystal material changes betweenits optical states through a range of voltages, the voltages applied todisplay 152 may be appropriately adjusted through the use of resistorsand display driver circuit 150 to correspond to the transition voltagesthat cause liquid crystal display 20 to change visual states. Also, byincluding different resistances connected to conductors 158, 162, and166, some level of voltage discrimination may be transferred to displaydriver circuit 150 for actuating different segments of a multi-segmenteddisplay. In other words, the voltages applied to the three segmentsshown may be scaled so that only one segment of the liquid crystaldisplay is activated at any one time.

FIG. 9 shows a third embodiment of the battery testing circuit of thepresent invention. As shown in FIG. 9, a display 200 is provided thatincludes many segments 202a-202h to provide a graduated scale to providea more accurate discharge level indication ranging between "fresh,""good," and "replace" as designated by indicia 206a-206c, respectively.Each segment 202a-202h is driven by a voltage discriminating/displaydriving circuit 208 via a pair of conductive strips 204a and 204bprovided for each segment. Voltage discriminating/display drivingcircuit 208 is coupled to the battery positive terminal by a conductivestrip 210 and to the negative terminal by a conductive strip 212. For aAA alkaline Zn--MnO₂ cell, for example, the open circuit voltage fallsfrom around 1.55 volts to 1.05 volts. Thus, the voltage discriminatingcircuit is preferably configured to activate one or all the displaysegments for cell voltages at or above 1.50 volts, to activate two orall but one display segments at voltages between 1.40 and 1.49 volts,etc., to provide an indication representing a gradual change in celldischarge level.

Those skilled in the art will appreciate that various configurations andconstructions may be used for the various circuit components withoutdeparting from the spirit and scope of the present invention.

The above description is considered that of the preferred embodimentsonly. Modifications of the invention will occur to those skilled in theart and to those who make or use the invention. Therefore, it isunderstood that the embodiments shown in the drawings and describedabove are merely for illustrative purposes and not intended to limit thescope of the invention, which is defined by the following claims asinterpreted according to the principles of patent law, including theDoctrine of Equivalents.

The invention claimed is:
 1. A liquid crystal display comprising:a firstelectrode provided on a substrate; a first liquid crystal layer providedon and in contact with said first electrode; a second electrode providedon and in contact with said first liquid crystal layer; a second liquidcrystal layer provided on and in contact with said second electrode; athird electrode provided on and in contact with said second liquidcrystal layer and electrically coupled to said first electrode; a thirdliquid crystal layer provided on and in contact with said thirdelectrode; and a fourth electrode provided on and in contact with saidthird liquid crystal layer and electrically coupled to said secondelectrode, wherein said first, second, and third liquid crystal layersare simultaneously activated by application of an electric field acrosssaid first, second, and third liquid crystal layers.
 2. The liquidcrystal display as defined in claim 1 and further including a displaydriver circuit coupled to said electrodes for creating an electric fieldacross said liquid crystal layers.
 3. The liquid crystal display asdefined in claim 1 and further including a printed display drivercircuit coupled to said electrodes for creating an electric field acrosssaid liquid crystal layers.
 4. The liquid crystal display as defined inclaim 1, wherein at least one of said liquid crystal layers is formed byprinting.
 5. The liquid crystal display as defined in claim 1, whereinat least one of said electrodes is formed by printing.
 6. A liquidcrystal display comprising:a first electrode provided on a substrate; afirst liquid crystal layer provided on and in contact with said firstelectrode; a second electrode provided on and in contact with said firstliquid crystal layer; a second liquid crystal layer provided on and incontact with said second electrode; and a third electrode provided onand in contact with said second liquid crystal layer,wherein at leastone of said second and third electrodes is made of a transparentprocessable conductive polymer and wherein said first electrode iselectrically coupled to said third electrode such that said first andsecond liquid crystal layers are simultaneously activated.
 7. The liquidcrystal display as defined in claim 6, wherein said transparentprocessable conductive polymer includes polyaniline.
 8. The liquidcrystal display as defined in claim 6, wherein said transparentprocessable conductive polymer includes dodecylbenzene sulfonic aciddoped polyaniline in toluene.
 9. A liquid crystal display comprising:afirst electrode provided on a substrate; a first liquid crystal layerprovided on and in contact with said first electrode; a second electrodeprovided on and in contact with said first liquid crystal layer; asecond liquid crystal layer provided on and in contact with said secondelectrode; and a third electrode provided on and in contact with saidsecond liquid crystal layer,wherein said liquid crystal layers are madeof a polymer dispersed liquid crystal material and wherein said firstelectrode is electrically coupled to said third electrode such that saidfirst and second liquid crystal layers are simultaneously activated. 10.A liquid crystal display comprising:a first electrode provided on asubstrate; a first liquid crystal layer provided on and in contact withsaid first electrode; a second electrode provided on and in contact withsaid first liquid crystal layer; a second liquid crystal layer providedon and in contact with said second electrode; and a third electrodeprovided on and in contact with said second liquid crystal layer andelectrically coupled to said first electrode, wherein said liquidcrystal layers are made of a polymer liquid crystal material, and saidfirst and second liquid crystal layers are simultaneously activated. 11.A battery label comprising:a label substrate for covering an outerportion of a battery; and a liquid crystal display provided on saidlabel substrate for displaying information pertaining to the battery,said liquid crystal display including:a first electrode disposed on saidlabel substrate; a first liquid crystal layer disposed on and in contactwith said first electrode; a second electrode disposed on and in contactwith said first liquid crystal layer; a second liquid crystal layerprovided on and in contact with said second electrodes; and a thirdelectrode provided on and in contact with said second liquid crystallayer and electrically coupled to said first electrode such that saidfirst and second liquid crystal layers are simultaneously activated. 12.The battery label as defined in claim 11, wherein said first and secondliquid crystal layers are made of a polymer dispersed liquid crystalmaterial.
 13. The battery label as defined in claim 11, wherein saidfirst and second liquid crystal layers are made of a polymer liquidcrystal material.
 14. The battery label as defined in claim 11, whereinsaid second electrode is made of a transparent processable conductivepolymer that includes polyaniline.
 15. The battery label as defined inclaim 11, wherein said second electrode is made of a transparentprocessable conductive polymer that includes dodecylbenzene sulfonicacid doped polyaniline in toluene.
 16. A liquid crystal displaycomprising a first electrode provided on a substrate;a first liquidcrystal layer provided on and in contact with said first electrode; asecond electrode provided on and in contact with said first liquidcrystal layer; a second liquid crystal layer provided on and in contactwith said second electrode; and a third electrode provided on and incontact with said second liquid crystal layer and electrically coupledto said first electrode such that said first and second liquid crystallayers are simultaneously activated.